A smart home environment may include sensors that monitor various aspects of an environment such as a home. Motion sensors may monitor rooms in the home for motion, and may be able to generate an alert when motion is detected in a room in which no motion is expected. Motion sensors may use passive infrared sensors, which may be able to detect heat sources within a room, and detect motion based on the motion of heat sources. Changes in temperature in the room, or the movement of heat source that is not a person, for example due to the HVAC system blowing air onto an object moveable by air, may trigger false alerts from a motion sensor that uses a passive infrared sensor.